M$=spam
Whereas in the past universities ran on Unix-like machines with RFC-compliant emails, in recent years M$ has invaded.
M$ strips the RFC-compliant Received: lines and adds hundreds of lines of its own garbage and randomly labels messages as spam.
One academic email forum to which I have belonged for ages got shifted to a M$ institution. Now I can't ignore my spam folder because half the messages from that list end up there.
That is, even when their authors' direct messages arrive in the standard mailbox.
M$ breaks everything.